Embodiments of the invention relate to an image sensor and a method for manufacturing the same.
An image sensor is a semiconductor device that converts an optical image into electric signals. The image sensor is mainly classified into a charge coupled device (CCD) image sensor and a complementary metal oxide silicon (CMOS) image sensor (CIS).
The CMOS image sensor includes a photodiode and a MOS transistor in each unit pixel, and sequentially detects the electric signals of each unit pixel in a switching mode to realize images.
In the CMOS image sensor, as a design rule is gradually reduced, the size of the unit pixel can be reduced, but the photosensitivity of the photodiode is also reduced. In order to enhance the photosensitivity of such an image sensor, a micro-lens is formed on a color filter. The micro-lens may be formed in a semi-spherical shape by performing an exposure process, a development process, and a reflow process on a photosensitive organic material. The micro-lens should have an optimal size, thickness, and radius of curvature depending of the size and the position of each unit pixel.